Sintered bearings are used while inner pores thereof are impregnated with a lubricating oil. In accordance with relative rotation of the sintered bearing and a shaft, the lubricating oil impregnated inside the sintered bearing seeps into a sliding portion with respect to the shaft. As a result, oil films are formed, and the shaft is supported through intermediation of those oil films. Owing to quietness and accuracy during high-speed rotation, such sintered bearings have been preferably used for fluid dynamic bearing devices to be incorporated in, for example, a motor spindle for information apparatus (for example, refer to Patent Literature 1).